Biophysical Markers of Suspected Preeclampsia, Fetal Growth Restriction and The Two Combined—How Accurate They Are?

Round 1

Reviewer 1 Report

The manuscript is of undoubted interest and can be published. In my opinion, the manuscript is well written and does not contain obvious contradictions. The authors themselves indicate a small amount of data, but statistical analysis allows us to draw adequate conclusions. I would like to recommend that only some of the tables be made in the form of graphs / figures, so that the presented results are easier to perceive.

Author Response

1. Comments and Suggestions for Authors

   The manuscript is of undoubted interest and can be published. In my opinion, the manuscript is well written and does not contain obvious contradictions. The authors themselves indicate a small amount of data, but statistical analysis allows us to draw adequate conclusions.

   Answer: We thank the referee for the positive evaluation  

   I would like to recommend that only some of the tables be made in the form of graphs / figures, so that the presented results are easier to perceive.

   Answer: We thank the referee for pointing out to the challenge reviewing the long and detailed table and respect In respect to the suggestion made to add graphs we added the following:

   1. The new Figure 2 and 3 shows the Spearman Analysis of the biophysical markers over gestational weeks (Figure 2) and BMI (Figure 3). Figure 4 describes the Sperman analysis of Doppler and angiogenic markers.
   2. A new Figure 3 is showing the regression analysis of the biophysical markers vs angiogenic markers sFlt-1 and PlGF. The graphs show that that mainly for the case of the FGR group, there is a strong correlation between low PLGF and high Doppler PI as markers for prediction this complication group, indicating each can be equally utilized with high accuracy in prediction FGR, as indicating in Table 2.
   3. Figure 5 shows ROC curved for each individual biophysical marker. It indicated the limited accuracy leading to the combined analysis as presented now in Figure 6. The figures covered the data summarized in Tables 3&4.
   4. We found no way to provide graphic analysis for multiple regression behind Table 5

    

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript submitted for publication to Reprod. Med. by Ziv Hospi et al., titled: "Biophysical Marker at Suspected Preeclampsia, Fetal Growth Restriction and The Two Combined – How Accurate they are?" is a study using secondary data aiming to assess biophysical suspected preeclampsia markers. The work is interesting with important potential clinical implications.

The manuscript is thorough and well referenced with good organization and reasonable structure. The reviewer would like to offer the following points to be considered by the authors:

1. BMI is an index and as such it does not carry units. The kg/m2 is a calculation and does not reflect units.
2. Consider stating your hypothesis/ses at the end of the introduction section.
3. Consider making a mention on the role of diet and body composition in regards to preeclampsia in the introduction and the discussion sections.
4. Although the dataset/participants is elsewhere described and the reference is given please consider providing power calculation and/or other means of scientific justification for the number of participants considered in the analyses.
5. Are there any particular reasons avatars/disadvantages regarding the Slovenian population for the aims of this particular study?
6. The authors should provide summaries for all the sub-sections of materials and methods in addition to the appropriate referencing in terms of references to dataset of primary data and study. That includes sub-sections 2.2 and 2.3.
7. there seems to be a problem with pagination after page 6. Please address accordingly.
8. The number of participants per groups seems fairly uneven how was that considered in the analyses? Please provide specific language to address that in the narrative.
9. The discussion section seems rather limited in considering the broader literature in the field and what other groups have attempted, researched and found and how conclusions compare. The authors are making references to previous work of theirs but there is not much consideration of other groups' works. The reviewer would recommend expansion of the section and more inclusion of other works.

Author Response

Comments and Suggestions for Authors

The manuscript submitted for publication to Reprod. Med. by Ziv Hospi et al., titled: "Biophysical Marker at Suspected Preeclampsia, Fetal Growth Restriction and The Two Combined – How Accurate they are?" is a study using secondary data aiming to assess biophysical suspected preeclampsia markers. The work is interesting with important potential clinical implications.

The manuscript is thorough and well referenced with good organization and reasonable structure.

Answer: We thank the reviewer for his positive general impression

 

The reviewer would like to offer the following points to be considered by the authors:

1. BMI is an index and as such it does not carry units. The kg/m2 is a calculation and does not reflect units.

Answer: Indeed, the referee is right. We reviewed the manuscript throughout,  and remove it from all places and from Table 1..

2. Consider stating your hypothesis/ses at the end of the introduction section.

Answer: We stated the detailed aim and the underlining hypothesis behind it at the end of the introduction page 3 lines 122-152. This is in line of the points also raised by referee 2. Hope it is satisfactory now.

1. Consider making a mention on the role of diet and body composition in regards to preeclampsia in the introduction and the discussion sections.

Answer: Indeed nutrition is important. Lack of calcium in the diet in South America is a risk factor for PE, and replenishing with Calcium could reduce the frequency of the disorder. Also, some studies described the role of anti-oxidant (and of dark chocolate) but large studies with vitamin E and C supplements failed to make an impact. Poor nutrition is linked to increased risk/prevalence of developing preeclampsia. Mediterranean diet is estimated to be suitable to reduce the frequency of PE. We entered a short phrase on this issue to the discussion lines 572-577.

Note, however, Slovenian women are not characterized by high BMI or obesity and their diet is often described as similar to the vegetable and fruit rich Mediterranean diet.

1. Although the dataset/participants is elsewhere described and the reference is given please consider providing power calculation and/or other means of scientific justification for the number of participants considered in the analyses.

 

Answer: Sorry for confusing the reviewer. The secondary analysis is not a nested case/control way of analysing prospective data. The analysis included all patients of the cohort, who all had a complete data set. The term secondary was made to indicate that the patients were analysed previously for some of the data, and in this study we analyzed additional items of the dataset.

We want to emphasize that this was not a screening study but we enrolled everyone who attended the delivery clinic once the woman agreed to participate and signed on the informed consent.

 

Regarding the study power: The prevalence of preeclampsia in Slovenia (pure PE and PE+FGR combined) is 2-3%. Our cohort included 73 cases of Preeclampsia (31cases of only PE and 42 cases of PE+FGR) corresponding to approximately 2433-3650 pregnant women. These numbers correspond to approximately 15-20% of all deliveries in Slovenia and for around 40% of the deliveries in the medical center of Ljubljana. In this respect, the cohort may be considered for having a power of 0.9 confidence which appears reasonable.  Of course, larger studies are warranted. We entered this account in lines 317-323 (sample description) and lines 679-688 (study limitations). .  

 

1. Are there any particular reasons avatars/disadvantages regarding the Slovenian population for the aims of this particular study?

 

Answer: We have now stated at the end of introduction that there were already larger cohorts, but here we conducted the study and analysis for a relatively small medical center with restricted staff time and resources. Our aim was to evaluate how best the biophysical markers can assist us in reaching clinical excellence despite the limited resources and personnel.

The performance of the biophysical markers was compared to the performance of the angiogenic markers as was previously published by us (11-14) for this cohort. We did it in order to inquire what appears advantages for a relatively small clinical setting like ours, and to help clinical sites like ours to choose the suitable methods of testing (according to available resource and staff expertise) to reach clinical decision, and whether one should prefer biophysical vs. biochemical tests in order to maintain high standards of clinical care. Page 3 lines 122-152

 

1. The authors should provide summaries for all the sub-sections of materials and methods in addition to the appropriate referencing in terms of references to dataset of primary data and study. That includes sub-sections 2.2 and 2.3.

 

Answer: If we correctly understand what the reviewer is asking, we added a section to the material and methods describing about what was known about this cohort [11-14], and what is included in the current secondary analysis .Lines 173-203

It covers the followinfs

In references 12-14 - same patients were analysed as the ones included here, and their basic characteristic were similar. However, the purpose of the study was different.

Reference 12 extracted the means, medians and inter-quartiles of 9 biochemical and biophysical markers with different accuracy, aiming to establish a differential marker profile to assist in the clinical management of PE, FGR, PE+FGR and PTD. Among other things, it showed that it is hard to differentiate between PE, FGR, and PE+FGR according to the pro-and -anti angiogenic markers, and that the Endo-PAT markers are important to separate PE from FGR cases, thus helping in developing differential diagnosis.

Reference 13 analyzed in depth the pro-and-anti angiogenic markers. In addition to Box and Wisker Plots it also included ROC curves of each marker, and their combination for the prediction of PE, FGR and PE+FGR.  The study has indicated that out of all pro-and- anti angiogenic markers (PlGF, sFlt-1, their ratio and sEndoglin), PlGF is the best marker of predicting FGR and reached diagnostic accuracy for the cases developed before 34 weeks of gestation, whereas the ratio of sFlt-1/PlGF reached this accuracy for the PE cases.

Reference 14 focused on the assessment of INHIBIN-A and evaluate whether it can add to the accuracy of prediction by the pro-and-anti angiogenesis markers. It showed that when combined with PlGF, INHIBIN-A offered similar accuracy to the prediction obtained combining PlGF with the ratio of sFlt-1/PlGF.

Reference 11 was an earlier study, and not all cases that are now available in the cohort were included. Among all markers that are now available in the cohort, it analyzed the pro-and-anti-angiogenesis markers and the Endo_PAT markers as best markers of all cases of PE.

 

Here we performed an in-depth analysis of the biophysical markers, and in certain points - we draw comparison to the performance of the pro-and-anti-angiogenesis markers.

 

1. there seems to be a problem with pagination after page 6. Please address accordingly.

 

Answer. The manuscript format isn’t easy to handle. Large tables require the use of horizontal format whereas the rest fit with the longitudinal format.

If accepted, the production manager will optimize the pagination, table positioning, etc.

 

1. The number of participants per groups seems fairly uneven how was that considered in the analyses? Please provide specific language to address that in the narrative.

 

Answer- Patients were enrolled as they attended the delivery and high-risk clinics. Among singleton pregnancies. In Slovenia, PE (with and without FGR) has higher prevalence than FGR, and accounts for 2-3% of all patients, whereas GR is less common and account to 0.7-1.2% of the deliveries, predicting a ratio of 1:3-1:4.3 in the number of anticipated cases. Thus, it is not surprising that we had 16 FGR cases compared to 73 (42+31), a ratio of 1:4.5. lines 317-323

 

1. The discussion section seems rather limited in considering the broader literature in the field and what other groups have attempted, researched and found and how conclusions compare. The authors are making references to previous work of theirs but there is not much consideration of other groups' works. The reviewer would recommend expansion of the section and more inclusion of other works.

 

Answer: There are 58 references in this paper, of which only 4 (7%) were from our group, additional 5 included highly cited studies by Prof. Nicolaides and 2 more by Dr. Meiri. Prof. Nicolaides has over 1300 papers in fetal medicine and he is probably one of the mostly cited individuals in the field, given his scientific and clinical innovative and pioneering work, his appointment as a foreign member of the National American Academy of Medical Sciences, and his editorial position in leading journals in the field. No wonder we used additional 5 citations of his work.

While revising this manuscript we added additional 4 references to other group research (ref. 43, 48-50) and in multiple places we added sentences to work by other groups for example lines 597-602, 632-633

 

With regards to extending the discussion, it appears to us that being humble and concise is probably a good virtue for handling the discussion of this paper. We reserve long discussions to future reviews on the subject. .

Author Response File: Author Response.pdf

Reviewer 3 Report

The study presents a secondary analysis of a database of a total 125 Slovenian pregnant women attending the high-risk pregnancy clinic due to suspected PE (n=31), FGR (n=16) and PE+FGR (n=42) from 28-39 weeks’ gestation and their corresponding term (n=21) 24 and preterm (PTD, n=15) controls. Mean Arterial blood Pressure (MAP), Uterine artery pulsatility index (PI) estimated by Doppler sonography, and reactive hyperemia index (RHI), and Augmenttion index (AIX%) determined by the Endo PAT were extracted from the database of patients who were tested at admission to the high-risk clinic with the suspected complications. Linear regression coefficients, Box and Whiskers Plots, Area under the Curve (AUC) of receiver Operation Characteristic (ROC) curves, and multiple regression were used to assess the marker accuracy using detection rate (DR) and false-positive rate (FPR) and previously reported cutoffs for estimating the positive and negative predictive value (NPV and PPV). SPSS, non-parametric statistics and Spearman’s Regression Coefficient were used to assess markers accuracy. The obtained results are clearly presented and elaborated in the discussion part. The conclusion is adequate.

Minor remark:

At the end of introduction part there is need to point out the novelty of present research and the research hypothesis and how it will be tested.

Author Response

Comments and Suggestions for Authors

The study presents a secondary analysis of a database of a total 125 Slovenian pregnant women attending the high-risk pregnancy clinic due to suspected PE (n=31), FGR (n=16) and PE+FGR (n=42) from 28-39 weeks’ gestation and their corresponding term (n=21) 24 and preterm (PTD, n=15) controls.

Mean Arterial blood Pressure (MAP), Uterine artery pulsatility index (PI) estimated by Doppler sonography, and reactive hyperemia index (RHI), and Augmenttion index (AIX%) determined by the Endo PAT were extracted from the database of patients who were tested at admission to the high-risk clinic with the suspected complications.

Linear regression coefficients, Box and Whiskers Plots, Area under the Curve (AUC) of receiver Operation Characteristic (ROC) curves, and multiple regression were used to assess the marker accuracy using detection rate (DR) and false-positive rate (FPR) and previously reported cutoffs for estimating the positive and negative predictive value (NPV and PPV).

SPSS, non-parametric statistics and Spearman’s Regression Coefficient were used to assess markers accuracy. The obtained results are clearly presented and elaborated in the discussion part. The conclusion is adequate.

Response: We thank the referee for his positive evaluation

Minor remark:

At the end of introduction part there is need to point out the novelty of present research and the research hypothesis and how it will be tested.

Answer: We thank the referee for raising this issue to help us clarify why this study is important and adds to the known body of knowledge available today.

A point by point paragraph was added to the introduction to explain the study aim, the challenging aspects for a relatively small medical institute, with personnel expertise but limited resources, and the relevance of this study to clinical work up and management. While we used known testing and analysis approach, the comprehensive and systematic evaluation enabled us to provide clear recommendation to medical center where set of expertise are available while others are at short, and where stuff time and resource are limited. (Page 3 lines 122-152)

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have made a reasonable effort to address reviewer’s comments. Proofreading is suggested.

Author Response

Referee: 

The authors have made a reasonable effort to address reviewer’s comments. Proofreading is suggested.

Answer: 

We carefully proof read the manuscript and made corrections. Thanks for this.

Kindly note the yellow marks to authors' name that were corrected

 

Author Response File: Author Response.pdf